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Consider the Standard Normal distribution. The mean is always ___________ and the standard deviation is always ________ .

Short Answer

Expert verified
Mean is 0; standard deviation is 1.

Step by step solution

01

Understanding the Standard Normal Distribution

The Standard Normal Distribution is a special normal distribution with specific characteristics. It is often used in statistics when dealing with standard scores or Z-scores, which are measures of how many standard deviations away a data point is from the mean.
02

Identify the Mean of the Standard Normal Distribution

In the Standard Normal Distribution, the mean is a fixed value. The mean is the center of the distribution, around which all the data points are symmetrically distributed.
03

State the Mean Value

For the Standard Normal Distribution, the mean is always 0. This is because it is standardized to have a mean of 0 by definition.
04

Identify the Standard Deviation

The Standard Normal Distribution also has a specific standard deviation. The standard deviation measures the spread of the distribution and in this standardized version, it is fixed.
05

State the Standard Deviation Value

The standard deviation of the Standard Normal Distribution is always 1. This ensures that calculations using this distribution are rescaled to this specific spread.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Mean of Standard Normal Distribution
When learning about the Standard Normal Distribution, one of the most important concepts to grasp is the mean. The mean is essentially the center point of the distribution. It's the value around which the data points arrange themselves symmetrically. In the case of the Standard Normal Distribution, this mean is consistently set to 0. This simplification is not arbitrary but serves a specific purpose: it standardizes the distribution, making it easier to work with. By having a mean of 0, statisticians and researchers can easily compare and interpret different data sets using the same baseline. This step is crucial in converting raw scores into standard scores or Z-scores, which we will explore later.
  • The mean acts as the reference point in the distribution.
  • All data points are symmetrically distributed around this mean.
  • In the Standard Normal Distribution, the mean is always set to 0.
Standard Deviation of Standard Normal Distribution
Moving on to the next critical element, the standard deviation of the Standard Normal Distribution is always fixed at 1. Standard deviation is a measure that tells us how spread out the values are around the mean. In simpler terms, it describes the extent of variation or dispersion. By setting the standard deviation to 1, the distribution is standardized, allowing easy application of statistical techniques and interpretation of Z-scores.
Using this configuration ensures that one unit of measurement or one 'standard deviation' is the yardstick, simplifying comparisons. The fixed value of 1 for standard deviation also supports calculated properties in normal distributions, helping in making precise predictions or assessments.
  • Standard deviation measures data spread around the mean.
  • In our special case, it's always 1.
  • This standardization aids in consistent measurement and calculations.
Z-scores
Z-scores play a fundamental role when working with the Standard Normal Distribution. A Z-score measures how many standard deviations a data point is from the mean of the distribution. In practical terms, a Z-score tells us about the position of a raw score relative to the mean, centered at 0.
If you have a Z-score of 1, it means you are one standard deviation above the mean. A Z-score of -2 means you are two standard deviations below the mean. Calculating Z-scores is essential for comparing scores from different data sets, especially when they have different means or standard deviations.
By utilizing Z-scores, you can adjust raw scores into a common scale, making it easier to determine how unusual or common a data point is within a given set of data. This is why the Standard Normal Distribution is such a valuable tool in statistical analysis.
  • Z-scores quantify the deviation from the mean in standard deviation units.
  • They enable comparison across varied data sets.
  • Positive Z-scores indicate values above the mean, negative below.

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Most popular questions from this chapter

Suppose a Normal distribution has a mean of 6 inches and a standard deviation of 1.5 inches. a. Draw and label the Normal distribution graph. b. What is the range of data values that fall within one standard deviation of the mean? c. What percentage of data fall between 3 and 10.5 inches? d. What percentage of data fall below 1.5 inches?

Poe, the Clydesdale horse has a world record breaking height of 20.2 hands. All Clydesdale horses have a mean height of 16.5 hands and a standard deviation of 1.85 hands. The last Great Dane to hold the world record for dog height was Gibson who was \(107 \mathrm{~cm}\) tall. Great Danes have a mean height of \(81 \mathrm{~cm}\) and a standard deviation of \(13 \mathrm{~cm}\). Which animal is taller compared to their respective breed? Explain your answer using Z-scores.

True or False: The bars of a bar graph should always touch.

Which sampling method is being described? a. A sample was selected to contain 25 people aged \(18-34\) and 30 people aged \(35-70\). b. Viewers of a new show are asked to respond to a poll on the show's website. c. To survey voters in a town, a polling company randomly selects 100 addresses from a database and interviews those residents.

A study is conducted to determine whether people learn better with routine or crammed studying. Subjects volunteer from an introductory psychology class. At the beginning of the semester 12 subjects volunteer and are assigned to the routine studying group. At the end of the semester 12 subjects volunteer and are assigned to the crammed studying group. a. Identify the target population and the sample. b. Is this an observational study or an experiment? c. This study involves two kinds of non-random sampling: 1. Subjects are not randomly sampled from a specified population and 2. Subjects are not randomly assigned to groups. Which problem is more serious? What effect on the results does each have?

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